1. Field of the Invention
The invention relates to an apparatus for linear illumination of a moving product web.
2. Description of Prior Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
EP-B-1 154 225 discloses an illumination apparatus for a moving product web which enables optimum scanning of the product web with the aid of a camera. This has both a directional and a diffuse light source in order to be able to scan the most varied product webs. This illumination apparatus has proved itself in practice and forms the point of departure of the present invention.
DE-A-39 28 159 A1 discloses a generic edge sensor which has a light source and a photodetector. Both the light source and the photodetector are surrounded by reflector screens which are in each case open towards the product web. This arrangement is adequate for the application of the transmitted light method. In the reflection method, in the case of which light source and receiver are arranged on the same side of the product web, it is, however, mandatory to illuminate the product web at an acute angle, since otherwise the light reflected by the product web could fail to be detected.